After a lot of trial and error i managed to get it installed after getting the same error messages about invalid certificate as many others here had.
What i did was rightclick on every file that was unpacked from the .rar file and under the General tab, on the bottom there is a text saying something like “This file comes from another computer and has been blocked to protect the computer” (i translated from swedish to its probably a little different in the original english) and next to the text is a checkbox with a text “Unblock” (again, translated from swedish), i did this for the first .exe and .vsto file and then in Application Files\Dose for Excel_3_1_7_5 folder, i did it for all the files in this folder as well, i did not do it for the files in the Resources folder
After this, i could install it.