That thing is trash.
Even if it mounts and doesn't break anything much more important like the CPU or motherboard the heat pipes don't look like they have full contact anymore. Minor damage to the heatpipe and pad interface will cause huge issues with heat transfer. Considering the cost of a cooler vs everything else I would not use it.
I've been using freecad for several years and it has improved a lot. I tried fusion and sketchup and a few other "freemium" options but features kept disappearing into the paid section so I decided to stick with something actually free and learn it.
I use the two dimensional sketcher the most. Find some tutorials about using constraints properly and it is very easy to use. The tech draw workbench lets you add dimensions and information in a printable format. Figure out how to do 1:1 scaling with your printer and you can make templates with perfect accuracy in minutes using only a few key dimensions.
Assembly is still a complicated process though. The assembly 3 and assembly 4 workbenches are great but pretty arcane. I don't remember which one I used last time I did a full multipart plan but the result was great. Basically they let you create anchors on lines and vertexs and such that then interact with each other across parts.
The trouble is in how those anchors interact with their parts. If you round an edge you just made some lines shorter. Was that anchor point attached to that line? Now it's in a different spot. Essentially you have to be perfect every step of the way and plan ahead or change many things for even a tiny change like a round edge.
With a little practice I've been able to get the assembly benches to make great results. You really have to do it correctly though or it all falls apart. The lack of in depth tutorials means you have to make a lot of mistakes and learn from them.
I would suggest trying freecad with either assembly bench. I'm not sure which one would be better suited to your needs. If it doesn't work for you paying for sketchup or fusion might be a better option. I think in a few years freecad will be very competitive but for now it lags behind on ease of use. Sometimes by a lot.