This message is usually presented as a compatibility alert, not an error. This means that the package in question was developed targeting that type of project and if some functionality is dependent on something unique to that platform, it may not work.
According to Microsoft documentation on the subject :
.NET Standard is the replacement for PCLs (offering a simpler, lightweight form of platform-independent code sharing (other than PCL that is oriented by profiles that represent platform intersections). In addition this new standard] is compatible with a subset of PCL profiles. .NET Standard 1.0, 1.1, and 1.2 overlap, each with a set of PCL profiles.
A quick google search should indicate some relevant results that explain this migration in detail, including major attention bridges, such as these:
How to make this plugin work with Visual Studio not giving the option to create PCL projects and only .NET Standard
If you already have a project created in PCL format you should be able to use it normally. Otherwise, as has been said before, it is likely that the plugin will work normally in a .Net Standard project, despite the alert. If the behavior is different from that, the interesting thing would be to specifically evaluate the issues in question (certainly not an alert message).
How do I make this plugin compatible with my project.
As available in package information , the Plugin BLE 1.3.0 project is open source. To become compatible, you must change the source code in accordance with the project contribution policy , including a release for support for the new .Net Standard pattern. You will need some domain ownership on NuGet packages
I hope I have helped.
