Are you sure that 'fixing' is even the right word? For most people, especially in AE, to fix means to repair; you call the repairperson to fix your dishwasher when it breaks down.
'Fixing/fixative sealant' might be right, but the verb could be 'to seal,' not to fix. There is a verb 'to affix,' but it's rather uncommon and probably not suitable for instruction manuals. If you're positioning something on a flat surface, like on a wall, another verb could be 'to mount.' Or if the 5 points are just the preliminary adhesive and you're going to add something else in between them to complete the seal, as in #2, the verb might be 'to anchor,' that is, to hold in the right place.
My completely nontechnical guess would be something like
Apply 5 anchor points of Tempo ... adhesive (mounting putty?) to the surface according to the diagram. Each anchor point should be at least 2 cm wide by 2 cm high.
I'm not sure I understand how a point can be 2 cm high/tall, but if it's a type of foam you might be able to use a word like 'dot,' 'circle,' or even 'blob'; if it's more like clay, maybe even something like 'ball,' 'lump,' 'blob' ... If the method uses both, you might call the claylike one the mounting adhesive or adhesive putty (or cement, or bond), and the foamlike one the sealant.
Maybe this will at least give you some ideas to search further on until someone appears who knows about Wärmedämmplatten.