What do I do if Salat Maghrib is up and I did not do Asr Salat? Do I do Maghrib Salat with Jama'a and after doing Asr Salat, shall I repeat Maghrib?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the Maghrib prayer in congregation has already started, pray with them first, then make up the missed ‘Asr prayer.

Allah knows best.