Meeting NCAA eligibility criteria is extremely easy. Anyone not currently meeting it typically just needs like one summer worth to get where they need to be. Happens all the time with European college basketball players since in Europe guys are usually not pursuing school when they pursue sports, so sometimes there's a bit of work to get them back on track if they are now looking at NCAA Sports.
There are two parts to this. One is meeting academic standards, such as taking right curriculum, grades, test scores, etc. That is what most people think of with NCAA eligibility. That is fairly simple, but unlikely to be issue here.
The second is
proving those those standards have been met. This later part can be tricky. Each recruit has to be a 'certified amateur' in order to be eligible. The NCAA's certification progress looks at student submissions, transcripts, schools comments and the school's accreditation. High schools that often send kids to NCAA have relationships with NCAA and makes for easier path as these schools are known entities. Furthermore, NCAA does not begin their certification process on any individual athlete until an NCAA coach requests it. They have limited investigative resources, so they want to keep it to legit D1 recruits only.
So there may be kids from Canadian High Schools that have never been through process with NCAA. That adds a layer of scrutiny and slows things down. Also, many of these players from juniors may not be on NCAA radar yet. So if a coach doesn't request their 'amateurism certification' from NCAA, the players won't yet meet eligibility requirements. (In the states, many kids will get this latter part done by end of 11th grade, even if they plan to defer and play a year in juniors, so that they can partake in showcase events and other recruiting events).
Its unlikely that all the players caught up in system are there due to poor grades, test scores.
The first year of changes will always be the slowest.