The DLL just needs to be in a place that all workers using the VBOs can see. You can either copy the file to each worker, or put it in a shared file location.
The image below demonstrates using a combination of references, using the PATH available to the application (includes any references in system PATH settings and the same folder that the executable lives in), as well as a direct file path. Both are valid. The full path in the image happens to exist locally on all systems I've deployed this particular VBO on. You could, in theory, instead supply a path to a dll on a shared drive (IE: "R:\Path\To\Reference.dll"). But again, there is a potential for networked share drives to not be accessible until Windows (not Blue Prism) has had a chance to open the connection first, most reliably done via File Explorer.
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Ami Barrett
Automation Developer, Team Lead
Blue Prism
Plano, TX
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