Sorry, I don't fully understand, and must guess: You cannot install any project into Laz 2.2.6/FPC 3.2.2 from the online-package-manager due to some issue with "tvplain"? What is "tvplain"? Do you mean "TvPlanIt"? And what is the error message? If it is "TvPlanIt": Was TvPlanIt already installed when tried to install further packages? Or is TvPlanIt among the packages that you want to install? And: what is your operating system?
Just tried to install TvPlanIt into Laz 2.2.6/FPC 3.2.2 on Windows 11, and it works flawlessly.