I installed one of the OpenGapp packages, no problem, on Saturday. Used the FlashFire method. Used one of the medium size packages, the micro or mini. Everything worked but slowly so decided to try the pico and reflashed the SD and installed the open_gapps-arm64-7.1-pico-20171203.zip. This time used Recovery and it failed with an error 64. The log file states "Installation Failure: this package cannot be installed on this device's architecture. Please download the correct version". Tried again with FlashFire and same error message. Then repeated with the the nano zip - same problem.
Any ideas, please?