It seems to me that you're having a problem registering the bot (correct me if i'm wrong).
I'm assuming your bot is working fine in Bot Framework Emulator
There are certain steps you need to follow to register your bot before testing it out on MS Teams (or any other platform). I'll list the method which doesn't require an Azure subscription but you will need a Microsoft 365 Account (same account you're using for Teams). You can also have a look at all the exhaustive methods to deploy your bot here
Expose your localhost as a web address (you can use ngrok for this)
Go to Dev Botframework- Register bot, sign in with your account and click on create a new bot. In the messaging endpoint paste your exposed bot endpoint and append it with /api/messages i.e https:4ety45.com/api/messages
You will get a Microsoft APP ID and Password, add it to your bots authentication/config (& manifest.json) file
Go to MS Teams, Appstudio and under Manifest Editor click on import existing app (if you already have the manifest.json file) else click on create a new app.
Make sure to fill out all the info and under bots sections, you should see your bot (add it if you don't) and make sure the messaging extensions are configured to your bot.
Click on test & distribute then install to test out the bot
