this upload of yours has not yet been officially added to IMSLP. You need to:
1) Go to the page for Boccherini
2) Click the link there to Add a piece to this composer page
2a) Give the piece a title such as "Quintet, Op. 30" (recommend you put Musica notturna delle strade di Madrid under an Alternate Title) and fill in any other info you know (the name of the composer will be supplied automatically)
3) Once you've done that, go to the page for "Quintet, Op. 30 (Boccherini, Luigi)" and click on the link to Add a file to this page
4) On the next page, select the link where it says Use this form for files already uploaded
5) On that page, the filename you uploaded was Quinteto_Op_30_Boccherini_Musica_notturna_delle_strade_di_Madrid_-_Partitura_Score.pdf. Please fill in the other info and click Submit!.