Help! Can’t send text messages, but can receive.

I bought a new Moto G Play and a new Mint SIM card. I can send/receive calls and I can receive texts, but I can’t send texts. I went through the troubleshooting in the wiki and nothing has helped. In the RCS menu I see “Status: Not Supported”, but I called Mint customer support and they assured me it was. They ran me through some troubleshooting that they “guaranteed” would work, but it didn’t. So frustrated here as a new customer. Anyone have any ideas?