Unable to add group to Cloud Policy

There are some limitation, you may consider:

1. Edit the existing policy
   If you want the same group to receive settings for both Word and Excel, you’ll need to consolidate those settings into a single Cloud Policy and apply it to the group.
2. Create separate groups
   If you need different policies for Word and Excel, consider creating separate security groups (e.g., WordPolicyGroup, ExcelPolicyGroup) and assign users accordingly.
3. Use priority-based targeting (if available)
   In some environments, policies can be layered using priority values, but this depends on the specific policy type and admin center. For Cloud Policy in M365 Apps Admin Center, though, it’s typically one group per policy.