Welcome to the community, @garbati1717! You could always validate your XLSForm through this online validator. The online validator should help you identify any syntax issues that are affecting the form deployment.
This post discussed previously should help you use the online validator.
By the way, it seems that your issue is related to the group structure. Every begin group must have a corresponding end group. You may need to download your form as an XLSForm and check that the total number of begin group and end group entries match. If they don’t match, the error message will appear.