It seems the only reliable way to print InDesign files (.idml) as PDF document is to use Adobe InDesign as no 3rd party software is know to us, that would be otherwise capable of IDML to PDF conversion. If you know anything else about this particular conversion, please let us know in the discussion below.
Convert InDesign Markup Language document to Adobe Portable document format.
We have found 3 software records in our database eligible for .idml to .pdf file format conversion.
Microsoft Windows software - convert idml to pdf on Windows
Professional desktop document publishing software from Adobe
Convert from idml file format
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 idml to pdf. 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 idml to pdf on OS X
Mac version od Adobe's popular document designing and publishing software
Apple's free authoring tool for making great looking e-books for iPads