Hi Gary,
Iāme setting up with Apache and MySQL - but 10.3 of ownCloud requires a non-Apple instance of PHP 7.3 that provides and modules.
ownCloud/Nextcloud stopped supporting OSX/macOS as a server platform for good reasons at a very early stage: There have been some strange charset behaviors and they decided not to engineer these āApple anomaliesā as there anyway have been only a few guys like you and I wanting to do such exotic stuffā¦ 
So, Iād strongly recommend you to set it up in any Linux environent as the Pi4 (I always found all older PIās as much too weak for appropriately setting up a cloud serverā¦! But the Pi4 now seems to be strong enough!) or a VM on the Mac.
I also did it that way and set up the Nextcloud environment inside an VirtualBox Linux VM on an OS X host. Including the letsencrypt stuff.
I tackled that with the help of a really cool tutorial - however it is in German what helped ME very much (Maybe you can also have some benefits from it, supported by Google Translator?? 
):
But honestly speaking, due to time limits I didnāt run this instance āproductionā so far, and meanwhile indeed it stopped working due to letsencrypt having been timed outā¦ So, I now need to find out to renew the certificate before I can go aheadā¦ (I hoped I had implemented a working automatism but obviously it doesnātā¦ 
)
And also, Iām still not completely happy with my current architecture itself - so I will need to do some further changesā¦