the launcher won't let me start the minecraft bedrock download

This exact same problem occured for me too. In my case the xbox app is logged in with my daughter's account, it's her computer, and the microsoft store uses my account.

Thank you for your report!
We're tracking this issue in MCL-21568, so this ticket is being resolved and linked as a duplicate.

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Hola te digo que lo mejor para ese problema es actualizar en Windows a la versión 22h2 o 21h2, y reintentes a mí me funciono y espero que a ti igual 
Mojan juegos 100/10

Mojan atención -500/10