They only allow original signature, so, carefully fill the form again, print them out, sign, scan back into the computer, send that pdf thr webform to them and explain. But also keep in mind that your application might be sent back to you due to incompletion (digital signature and some mistake you have stated earlier).
In that case, i assume your nomination certificate will expire, so, you need to email them and ask for an extension, then, when you have the new nomination certificate,then you can send your application again. This, will take roughly 7month more (2month for extension and 5-6months for new AOR)
All the best.