As both the PPTX and POTM files are from Microsoft PowerPoint, the most easiest solution would be simply re-save PPTX to POTM using that program. This will create a template based on the presentation with possible macros enabled.
Convert Microsoft PowerPoint Open XML presentation to Microsoft PowerPoint 2007/2010 macro-enabled Open XML template file.
We found 4 software records in the database related to .pptx to .potm file format conversion.
Microsoft Windows software - convert pptx to potm on Windows
A presentation program from the Microsoft Office suite
Convert from pptx file format
|Yes, Microsoft PowerPoint supports pptx file conversion as a source file type.||Yes||Yes||pptx editor||Yes||No||No||No|
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned pptx to potm. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert pptx to potm on OS X
Mac version of popular presentation software from Microsoft
Multiplatform software - convert pptx to potm on any platform
Powerful multimedia presentation software tool from LibreOffice suite
Free presentation program from OpenOffice.org