Overview
The dialog/prompts for checking in and checking out pdf files (when double clicking) needs some configuration and explanationSolution
PDF files are, generally, not editable, and so they do not check out when opened by default.It can be configured through UI.
Right click the M-Files icon in the taskbar > Settings > M-Files Desktop Settings > select the Settings tab > User Specific Settings > Behavior by File Extension.
In the .pdf extension, choose what the action should be (read-only which is the default, check out, or ask).
Do this for other file types that are listed explicitly.
There is a setting on what to do with all file types that are not listed.
The same dialog also has a default behavior for checking in (it defaults to Ask).
In the Settings tab of the Desktop settings, there is also the Export section where you can export the registry keys from the current machine to a .reg file. for distribution to other machines.
PDFs are generally supposed to be immutable, so if documents need to be edited, it is suggested to do so in an app like MS Word and use PDF conversion (e.g., in a certain workflow state) to make PDFs when the documents are finalized.
The check-in prompt is generally tied to editing so it is best to setup checkout first.
There are also some known issues with Acrobat Reader that does not check-in automatically, you can see how to fix it here: https://m-files.force.com/s/article/Automatic-check-in-not-working-for-PDF-files
