I think this is probably a pretty simple question, but I have a habit of making things sound more complicated than they really are:

We're new to Apple Business Manager and MDM software, so I'm still pretty unfamiliar with how any of this works. We're currently evaluating the MDM product provided by ManageEngine, and we're using Apple Configurator installed on an iPhone to add our existing devices to ABM, and then from there to the MDM via the link between ABM and the MDM. Most of our iPads are relatively new, however we do still have a bunch of original iPad Air and iPad Air 2 devices, which is presenting a problem for us because they don't support the iOS version currently needed to be able to add them to ABM via Apple Configurator installed on an iPhone; thus, we're having to use Apple Configurator installed on a Mac, rather than an iPhone, to try and add them to ABM. The idea, once again, is to first add them to ABM, and then from there add them to the MDM via the link between ABM and the MDM.

I'm following the instructions to do this here:

However, I'm running into an issue: After resetting, the iPad gets stuck during initial setup at the Remote Management screen, with the message "The configuration for your iPad could not be downloaded. The request timed out." My wild guess is that this is due to step 4 in these instructions, in which we leave the MDM Server URL field unchanged; this causes the URL in the blueprint to be "https://myserver.local/devicemanagement/mdm/dep_mdm_enroll", which the iPad is unable to resolve. (On a side note, the Wi-Fi profile we select when creating the blueprint doesn't seem to accomplish anything; I still have to manually enter the Wi-Fi connection details during initial setup on the iPad. I'm not sure if that's relevant to this issue though)

If instead, though, in step 4 I enter our MDM server URL, it works; the iPad shows up in our MDM. Furthermore, by entering our ABM organization info in step 6, the iPad also shows up in ABM. Thus, the iPad's in both ABM and the MDM. Which is what we want, right? I mean, I'd prefer to add the iPads to ABM first, and then to the MDM via the link between the ABM and the MDM, like how we're doing it with our new-ish iPads; but since that doesn't seem to be working, I'm having to enter the MDM server URL into the blueprint to get them to show up in the MDM.

So my question, since this is all so new to me, is: Most of our iPads (all the new-ish ones) will be added to ABM via Apple Configurator installed on an iPhone, and then added to the MDM from there via the the link between the ABM and the MDM. However, some of our iPads (all the old ones) will be added to the ABM and MDM simultaneously, as outlined above. Is there any practical difference between the two? The MDM shows the new-ish iPads as being enrolled via "Apple Dep", while it shows the old-ish iPads as being enrolled via "Apple Configurator". Could this end up being a problem for me in the future in any way?