The universally-available Adobe Reader software is used to print these "PDF" format map files - it should already be installed on your computer. After downloading the PDF file, you should "Open" it in Adobe Reader - often your browser will automatically do this after the download completes. In Adobe Reader, click on the "Printer" icon (or select the "Print" option under the "File" tab) to bring up the "Print" window. You should ensure that the "Auto Rotate and Center" and "Portrait" options are checked. Then look at the "Page Scaling" selection - on many printers the one-page "Big Sur Trailmap sections" can be printed with "Page Scaling" set to "None", but if your printer chops off the map or its printable area is not centered on the page, then use "Fit to Printable Area". I have tried to make the map as large as is possible for the average printer, but your printer's "printable area" may be smaller-than-average. Finally, click the "OK" button to send the file to the printer. The options you have selected should be "sticky", i.e. will automatically have become the default options the next time you use Adobe Reader.
High Quality Printing
Print quality is dependent upon a PC's printer settings. Here is how my my HP PSC-750 printer works with Adobe Reader - likely your printer works similarly. If I print using Adobe Reader as described above, my printer's "Normal Quality" light blinks and the printer prints at 300 dpi (dots/inch). I can instead produce higher-quality 600 dpi prints by, in Adobe Reader's "Print" window, first clicking the "Properties" button, then clicking the "Printout Mode" tab, then selecting "High Quality" and clicking "OK" - then while printing the printer's "Best Quality" light blinks and the page takes about three times longer to print. However, this setting is not "sticky" after closing Adobe Reader, i.e. the next time I open Adobe Reader to print a map section I must again make that change, else it prints as "Normal" quality. Note that once you have changed to "High Quality" printing that setting will remain in effect for printing of subsequent maps if Adobe Reader is not closed - so if you have multiple maps to print at the same time, you can change to "High Quality" printing for the first map and then simply keep Adobe Reader open to load and print each subsequent map, without having to make any printing changes for the other maps.
I cannot create a PDF file that will automatically force the printer to use its "High Quality" setting - the default print quality is determined by the PC's printer setup and can only be altered manually, at print time by the user. Differences between the 300 dpi and 600 dpi printouts may be seen in the printing of tightly spaced contours - for my eyesight and printer the differences are not really noticeable, but your results may differ. Whether an increase in print quality is worth the hassle of having to change the "Printout Mode" each time your open Adobe Reader is for you to decide. (Note: the map image in the PDF file has a resolution of over 600 pixels/inch, so printing at 300 or 600 dots/inch is accomplished by "downsampling" the image resolution to the printer resolution.)
For outdoor use, consider using an inkjet-printer-compatible synthetic paper - both sides are printable without bleed-through and they are tear-resistant, grease-resistant, and water-resistant (~$0.50/sheet) or water-proof (~$0.90/sheet). One on-line source is iGage Paper. REI currently sells tear-resistant, water-proof National Geographic "Adventure Paper" at their Marina store for $1/sheet.