A file attachment section consists of one or more uploaded files. This section is the one to use if there is no more specific section for your data, e.g. videos and images.
There is no limit on file size per se, but your server administrator might have imposed local restrictions. Thus see your local recommendations. However, certain types of raw data are better stored other ways which provide more specialized access. For example, raw microscopy images can be stored in OMERO or PACS servers. Raw sequencing data (FASTQ, SAM, BAM) should be delta-compressed (not zipped) before they are small enough for final archiving. The tools for this are evolving rapidly and not listed here.