What is the prayer that must be performed upon waking up late for Asr prayer, while the congregation is standing for Maghrib prayer, and there is another congregation praying Maghrib later?

The 'Asr prayer has become a missed prayer (fāʾitah), so it should be prayed with the intention of making it up (qaḍāʾ). It must be prayed first, before the Maghrib prayer (the current prayer), because the order is obligatory. The questioner can pray with the congregation performing the Maghrib prayer with the intention of making up the 'Asr prayer, then complete it after they finish their prayer. This is permissible according to some scholars to attain the virtue of congregational prayer, and the difference in intention between the Imam and the follower does not affect it.