Hi @Juan Sebastián Cortés Villegas,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
The error with the RD agent downloads in Azure Dev Center usually means the required WVD URLs are not reachable. To fix this, check your network connection, make sure the needed endpoints are accessible, and if the dev box is still not working, try deleting and recreating it.
If you have any further queries, do let us know.