This error happens when your computer is missing a specific Microsoft software package which enables the installation of Microsoft Office Add-Ons.
Your administrator has blocked this application because it potentially poses a security risk to your computer.
This error can occur if your security settings are different than the Windows standard settings (and therefore do not allow the installation of so-called ClickOnce applications).
System.Deployment.Application.InvalidDeploymentException: Exception reading manifest from file:///C:/Users/XXX/AppData/Roaming/SlideLizard/Installer/SlideLizard.PowerPointAddIn.vsto: the manifest may not be valid or the file could not be opened. ---> System.Deployment.Application.InvalidDeploymentException: Manifest XML signature is not valid. --> System.Security.Cryptography.CryptographicException: SignatureDescription could not be created for the signature algorithm supplied. at System.Security.Cryptography.Xml.SignedXml.CheckSignedInfo(AsymmetricAlgorithm key) at System.Security.Cryptography.Xml.SignedXml.CheckSignatureReturningKey(AsymmetricAlgorithm& signingKey) at System.Deployment.Internal.CodeSigning.SignedCmiManifest.Verify(CmiManifestVerifyFlags verifyFlags) at System.Deployment.Application.Manifest.AssemblyManifest.ValidateSignature(Streams)
If you get a similar error to this, you need to allow the installation of ClickOnce applications(for more information check out https://docs.microsoft.com/en-us/visualstudio/deployment/how-to-configure-the-clickonce-trust-prompt-behavior?view=vs-2019).