Update: After a lot of tinkering, I got it to work. Thanks for the advice for non-computer science people like me.
I followed your advice for the DLL file, “The DLL needs to go into one of the folders that are included in the PATH environment variable. Open a command prompt and type PATH, then copy the DLL to one of the paths listed there.”
I still had trouble getting the OFX folder in the right place for Resolve to recognize it, and read the read me file stating I should put the OFX folder in the c:\Program Files\Common Files\OFX\Plugins\ and was confused because Resolve did not create one, and I only thought of making one myself after trying all the other conceivable locations around the Davinci Resolve program directories. I am just putting this up here in case someone else is trying to figure out the same thing (set up G’mic OFX in Resolve on Windows 10), to tell them that they actually have to create an OFX folder in the directory c:\Program Files\Common Files, and then create a folder labeled plugins inside that to put the GMIC_OFX.ofx.bundle folder inside the plugins folder.
Also, I did not find the inverse fourier transform option in the plugins, so all the G’mic filters could do is the initial fft, but not get me back after I do my frequency domain edits. Is it included in the G’mic OFX plugin set but mislabeled, or do you have any advice about alternative Resolve FFT plugins?