Yes. The way you can parse it is:

A creature must also make this saving throw when [(it enters the spell’s area for the first time on a turn) or (ends its turn there)].

Clearly, the conditions are:

• The creature enters the area for the first time on a turn
• The creature ends its turn there

Note that this is different wording than something like Cloud of Daggers which says:

when it enters the spell’s area for the first time on a turn or starts its turn there.

Whether this was intentional or a mistake is a different matter.

Yes. The way you can parse it is:

A creature must also make this saving throw when [(it enters the spell’s area for the first time on a turn) or (ends its turn there)].

I interpret the 'or' as joining the two conditions with the saving throw requirement (as if there were an 'either' in front of the two conditions), so the phrase means:

• If the creature enters the area for the first time on a turn, it must make a saving throw

AND

• If the creature ends its turn in the spell, it must make a saving throw

are both valid conditions for the spell to force a creature to make a saving throw.

Note that this spell functions slightly differently than something like Cloud of Daggers which says:

when it enters the spell’s area for the first time on a turn or starts its turn there.

Which makes it much harder to trigger both of the saving throws yourself (but still possible).