The supported file formats for Turnitin originality check are
- Adobe® PDF
Microsoft PowerPoint® (.pptx, .ppt, .ppsx, and .pps)
Microsoft Excel® (.xls and .xlsx)
A LaTeX file should be converted into PDF-format with PdfLaTex: take a preview of .tex source code and a pdf file is created. Note, that not all converted pdfs are accepted by Turnitin. For example, according few experiences, xetex/xelatex will produce pdf version that looks fine, but is not readable by Turnitin, while luatex/lualatex seems to works ok with Turnitin.
A file should contain at least 20 words. The maximum file size per a submission box is 40MB or less than 400 pages. If the file is bigger than that, you have to split it into two separate files and submit the first one into Part 1 and the other one into Part 2. By default, there is only Part 1 in a submission box. Teacher can add parts by editing the settings.
See a full description of restrictions in submitting files in Turnitin guides.