If possible I go for a "clean" install and use the latest available full installers rather than going through a bunch of patch updates.
First thing to do is to make a backup of your content, both custom and default/purchased. Next uninstall both iClone and 3DXchange using the RL uninstallers found under Programs->Reallusion.
This action will also remove all RL default content, it should in no way affect your custom and/or purchased content - but you have your backups just in case.
Now is a good time to defrag your disc before doing a fresh install.
Install iClone 5.4 and 3DXchange 5.4 using the IC5_PRO_Enu_Online.exe and ic3DXchange5pro_Enu_Full.exe files downloaded from your account.
Next install the iClone Bonus pack and the IC50Bonus_G5_Outfit_Developer_Collection - for some reason the iClone installer always points you to the download for this pack even though it is installed.
Open iClone, have a look at what content you have. If everything went according to plan then you should now be a happy cloner.
System: Win 10 Pro (1803), Asus X99-E WS, CPU i7-5930K -3,5 GHz, 32 GB DDR4 2666-16 RAM, NVidia GTX 1080 Ti GPU - 11 GB VRAM(Driver 417.35), Samsung 850 Pro 512 GB SSD, 6 TB HD storage.