This package appears to have a custom/proprietary license agreement, and ProGet cannot be automatically determine the license type. You'll need to assign a license type to the URL to allow or block packages with this license.
To install AjaxUploader from the command line, run the following command:
nuget install AjaxUploader -Version 4.0.2.2 -Source https://nuget.sapec.md/nuget/Sapec/
To install AjaxUploader from the Package Manager Console within Visual Studio, run the following command:
Install-Package AjaxUploader -Version 4.0.2.2 -Source https://nuget.sapec.md/nuget/Sapec/
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageReference Include="AjaxUploader" Version="4.0.2.2" />