Your link documents that Brooks was in the custody of Atlanta police in January, 2020 for a probation violation. It doesn't tell us what happened between that date and the night of his death. There is no mention of a basis for any arrest warrant that the officers in the instant matter may have known about.
If Brooks did miss a meeting with his probation officer, there may well have been a warrant out but the facts known to the public suggests a warrant wasn't in play insofar as the officers were concerned. Brooks, of course, had good reason to worry about being arrested.