The modern social justice cult divides people into groups based on how "oppressed" they are, and assigns more rights, privileges, responsibilities and guilt onto people based on which such group they belong to. At the very bottom of the barrel are, of course, white men (although jews might or might not be even lower, depending on the social justice warrior). White women are just slightly above them, because they are women (and thus more oppressed than white men).
White people in general, and white men in particular, are considered the bottom of the barrel in more than one way. Not only do they get no respect, consideration or rights in the eyes of social justice warriors, and not only are they despised, vilified and hated, but to an increasing extent social justice warriors think that white people are pretty much a different species from other people, who are literally, not just metaphorically, genetically predisposed to racism and oppression. It's literally in their DNA, and is something that every single white person inherits (and nobody else, of course). White people are literally an inferior race, not just socially but genetically, and many social justice warriors express the sentiment that the world would be better if they were exterminated and completely eradicated from the face of the planet. (And then they call their critics "nazis", and are completely oblivious to the irony.)
An "ally" is, to them, a member of this inferior race that's subservient to the social justice cause.
It's very similar to the concept of a "dhimmi" in Islamic culture and religion: A person who is not a member of the religion, an outsider, but who is subservient to it and its members, and obeys everything that the actual members of the religion want, and pays tribute (often in terms of money) to the religion. Dhimmis are tolerated, but they will always be inferior and will never get the same rights and privileges as actual members of the religion, and must always be subservient to the religion.
As an "ally", you will still be considered to be on the bottom of the oppression stack, just a tiny bit better than the rest of white people. You will have to be subservient to the superior races and groups, and do everything they want, never talk back, never present a dissenting opinion, never criticize anything that the superior groups say. If you are a white man, and a woman or a non-white person starts talking, you must immediately and subserviently shut up. You must never interrupt or talk over a member of the superior groups. You must always follow the orders of your superiors, even if doing so would get you in trouble (eg. with the authorities). And you must always remember your place.
I wish I was exaggerating or making those things up, but all of those are things I have seen concrete examples of, in articles, blog posts and YouTube videos. Examples of social justice warriors explicitly and literally saying and enacting all those things (even including that part about white people being genetically inferior, and racism and oppression being literally part of their DNA, as well as that part about such a white person being commanded to obey orders even if it gets him in trouble with the police, precisely because of his genetics and the associated guilt.)
If you submit yourself to be an "ally" of social justice warriors, you will never get the same rights and privileges as the "superior" races and groups. You will always be subject to and forced into submission, and you will always be used and taken advantage of, and no matter what you do, you will still be vilified and oppressed, and not only will any differing opinion of yours not matter, it will actually not be tolerated. You will only be tolerated, barely, if you fully submit and commit to the ideology, without question and without criticism, and if you constantly humiliate yourself by confessing your sinful nature to the superior groups, and pledge your allegiance to them.
You are not a person to them. You are a useful tool. A tool that does not have the same rights as the superior groups. In other words, you will pretty much in essence be a slave. A slave that will be punished if he shows any disobedience or dissent.
I will never degrade myself into this, and neither should you!