I will confess my ignorance of both Usermanager and Hotspot immediately.
I have been using MikroTik boards for a few years but just haven't had to deal with authentication and radius servers-now I do. Here is the setup:
MT 493 AH running 5.13, usermanager 5.13 installed.

ether1-gateway- 10.1.4.3/29
ether2- DHCP client network 192.168.2.0/24, 192.168.2.1 DHCP server
ether3- DHCP client network 192.168.3.0/24, 192.168.3.1 DHCP server
ether4- DHCP client network 192.168.4.0/24, 192.168.4.1 DHCP server
ether5- DHCP client network 192.168.5.0/24, 192.168.5.1 DHCP server

everything is maqueraded out ether1

The goal: random client connects, is logged in automatically and is presented with total download/upload bytes since first login. Client is disconnected when a preset limit is reached (say 5GB down, 1GB up). Connection speeds controlled by either Usermanager or PCQ?

The question: I don't know if both Usermanager and Hotspot are required to accomplish this, or just one or the other.
If both are required, can their IP address both be 10.1.4.3 on ether1, or do I need 4 instances of Hotspot, one each on of the 4 LAN subnets?

Thanks very much if you can point me in the right direction. I have read everything I can find, but I'm still spinning my wheels at step 1.

Thank you Normis.

So in my case it would be best to run 4 hotspot servers, one on each subnet, and instruct them to use radius?

I have read that Userman log files can occupy a lot of disk space.
Can logging be turned off right from the start?
I don't need to export any database files, only keep track of cumulative bytes and shutdown or slow down a client when the preset limit is reached.

Thanks for the help.

Yes turn off logging it takes up alot of space!

I have a very similar setup, specify the pool names in the profiles section for each subnet you are using.

You will setup the upload/download limits in userman but setup a PCQ in your routerboard under queues