Adobe DC is supposed to have a checkbox in the Comments section of Settings (the last checkbox) that says "Auto detect pen hardware to enable markup". For some reason, it is missing on some of my computers that are using the same Windows 10 operating system and the same current version of Adobe DC. It is very frustrating because the absence of the checkbox means that you can't immediately markup a document with a pen and instead need to click through several layers of buttons in the comments section in order to use the pen. It is clearly a "glitch" that is appears in some installations and not others. I have seen that other people have complained about this also.