Hello Giovanni,
The MC upgrade is not available for AS v4.3+, because they were renamed to be Acp10Arnc0 Technology Packages for AS v4.3+. You need to install the AS4_TP_Acp10Arnc0… version instead.
AS v3.x = AS3.0_MC_Acp10…
AS v4.0-4.2 = AS4_MC_Acp10…
AS v4.3+ = AS4_TP_Acp10Arnc0…
The root of the issue is that you won’t find the Technology Package version on the website or Tools > Upgrades, because it is subject to dual-use regulation. To get this version you must contact your local support office for your country: Locations
Best regards,
Austin