The best way for keeping all sample information in one place is to keep it in the sample table. Sample table does not enable uploading files for the time being but you have a possibility of uploading the files associated with the sample under the Results section.
You can also copy-paste the hyperlinks of your files associated with the samples in a custom column in the sample table. Of course, that would mean that the files would need to be originally stored on some cloud account (e.g. Drobox, OneDrive, Google Drive). In this case you would create different custom columns, for example "NMR", "MS" or "chromatogram" and paste the hyperlinks in the table cells (see the image below).
Once you click on the hyperlink, a new browser tab opens, where you can view or download the file.
You can also associate an individual sample with other samples or with the projects, experiments and tasks, for that matter, by using the symbol "#" (see the image below).