Getting Exceeded max size limit of 6000000 Error while Merging/previewing

We are getting the below error while trying to convert/merge the below document template:

System.HttpRequest[Endpoint=https://api-mirror.aspose.cloud/v4.0/words/merge_Branded%20Print%20Invite%20Mv6_AUS-47931%20Virtual_v2.docx?fontsLocation=customFonts&format=PDF, Method=GET]

System.CalloutException: Exceeded max size limit of 6000000

Document Template:
Branded Print Invite Mv6_AUS-47931 Virtual_v2.docx (3.2 MB)

Please look into the issue.

It’s not our limit, but SalesForce so we can’t fix it