DigiDoc3 crypto was not designed to encrypt large files.
When you try to encrypt for example 100MB file in DigiDoc3 crypto then the process will take a very long time. Additionally during encrypting your computer might become very slow and unresponsive. It's very likely that encrypting will fail and you will either get an error or crypto will simply crash.
When there is a need to securely share large files then some alternative should be found. It's recommended to use DigiDoc3 crypto for document encryption for files smaller than 100MB.