Also, I tried to add text and URL to the Documents tab in the UI, but it seems like the edits are not persisted to mySQL? I see no changes in the DB and refreshing the page just erases all the edits I made to Documents.

It's working fine for me. Did you check logs of datahub-mae-consumer? You can also just check docker-compose logs. I could see the method being called up in the log. It looks like

datahub-mae-consumer   | 08:31:45.261 [mae-consumer-job-client-0-C-1] INFO c.l.m.k.MetadataAuditEventsProcessor - {com.linkedin.metadata.snapshot.DatasetSnapshot={urn=urn:li:dataset:(urn:li:dataPlatform:glue,bfl-staging-dms.product_m,PROD), aspects=[{com.linkedin.common.InstitutionalMemory={elements=[{createStamp={actor=urn:li:corpuser:datahub, time=1619944288983}, description=Website, url=<https://abc.ai>}]}}]}}

ok, i realised the problem was that i was not logged in as a valid user, so the UI kept rejecting my edits. once i added a user (using the bootstrap.mce as example) and "logged in", it worked fine