Distributing Apps Private / Corporate Set of Users

Hi,

Does anyone have any tips on distributing applications privately to a set of staff? I have been reading this afternoon on how to distribute our first application to a small set (100) staff. We have their google play email addresses and I thought it was going to be straight forward. However having just read many articles on google's developer sites it seems we have to use an EMM to do the final distribution. Is this true? We hadn't factored costs for an EMM and we are not sure how our staff will react to us suddenly wanting to manage their devices. We just want to distribute one application. At the moment it is looking like it'll be easier to send them all the apk and have them set their phones to trust untrusted apps!! That will appear incredibly unprofessional, but not as bad as suddenly forcing them to install managed play or whatever permutation of those words google call it (incredibly self contradictory guides resulting from a recent name change apparently) and an EMM and a registered google account etc.

If anyone knows of an easier way or if I'm missing something and we don't really need to pay user licenses for an EMM and install it on a LOT of phones I'd really appreciate it.

Thanks,
Danny