In my experience clematis will grow with very little sun, but they won't grow robustly and they won't bloom with less than about 4 hours of sun, and some seem to want considerably more than that to bloom well. I have one trellis that gets about 4 hours or a bit more of morning sun and of the 4 clematis on it, one is in its first year so isn't blooming yet, one of the texansis hybrids (probably Princess Diana) blooms though not as densely as in more sun, Polish Spirit doesn't bloom at all though it's the oldest, and Aphrodite, planted last year is blooming well. They get relativly bright shade in the afternoon since they are planted on the east side of a large building and have trees 40 feet or so to the south.

In order to have success with clematis, it's easiest to grow viticella hybrids to start. Regardless of what kind, they should be planted a few inches lower than they were in the pot and the soil kept moist but not soggy. Mulch will help keep the soil moisture even. Clematis don't like root competition; how close is that maple tree?

I've read that Claire de Lune clematis is more shade tolerant than some others.

Lots of Clematis are supposed to be 'shade tolerant'. I am with nhbabs here. 'Shade tolerant' just means that Clematis will grow and look healthy, but it does not mean it will bloom well (what is the point of having it?). I am going to move all my 'shade tolerant' Clematis to more sunny locations. 'Claire de Lune' is not an exception - it throws a handful of blooms for me during the growing season (west location, some direct sun with bright/dappled shade).

And I am also wondering how close is that maple. If the spot for Clematis is within the drip line of the maple or very close to it, it is not a good idea to plant ANY Clematis there.