First of all welcome to 3D printing! It has it’s joys and frustrations, and this is definitely one of them: getting the first layer flawless. The nice thing is, once you get this figured out, it makes it a lot easier.
I will tell you one thing for certain, especially when you are starting out. It is usually easy to assume a problem with the slicer, or the filament, but 100% of the time my problems have never actually been from either of these. You can got to https://tools3d.azurewebsites.net just in case, and repair the STL just in case.
When describing the problem, it is very important to know the exact set of events which are happening. “Starting to glob” is not going to be descriptive enough for me to diagnose, but I can make a few guesses to help you approach this algorithmically.
Is the nozzle too close or too far?
This is a critical question you need to answer. Look at visual guides for what first layers should look like, for example HERE
You can usually tell if you watch carefully. A nozzle that is too close can scrape against the bed, causing no extrusion, and damaging the bed. This will both jam the nozzle and cause the filament to grind into the knurled bolt (which you should clean out just in case), and cause worse complications later on. If the plastic is extruding, but squeezing out the sides too much, this will create poor adhesion. If the nozzle is too far, the plastic will not hit the bed, causing poor adhesion.
Poor adhesion causes the print to come loose and fail. Your perfect first layer will have a very distinct look to the plastic bead, and you will have to develop an eye for this, since 3D printer z-axis can be imprecise and need constant adjusting. You can not only level your bed properly, but adjust your initial z-height which is a critical process. I had run 3 of the same printer model, and each one needed a different initial z-height to get a perfect first layer.
The other factor that will create poor adhesion is if the plastic is too cool on the first layer. I typically print closer to 205 or 210 sometimes. Cura should have advanced settings that allow you to adjust the temperature and layer height for the first layer only.
Another factor is if the bed is too cool or too hot. This heavily depends on the printer surface, but for PLA I use 40-50 C, but I have PEI sheet which allows me to print cooler and stick. You may need higher for glass or different surfaces.
Most notably: 0.3 mm nozzle is a very tight aperature and 0.1 mm layer height is very fine . This is a more advanced print you are attempting as a beginner, in my opinion. I do an initial layer height of 0.425, but I have a different printer and a 0.5mm nozzle. For you, if nozzle swapping isn’t possible, one option is to slow the print down, which helps solve problems for a variety of issues. Another option is to increase the layer height to more like 0.3mm… I would highly recommend starting with larger layer widths as a beginner. Keep in mind when you change the layer height, you may have to adjust the initial layer settings, or the initial z height.
If you are using PLA, a trick a lot of people use is to cure the nozzle with oil. You can look that hack up as well. I myself during long prints will oil at certain times if I am going to be away for many hours, and I’ve completed long 30+ hour prints.
Remember, try changing one thing at a time. If it fails, try and reset and adjust a different thing, or the same thing to a further degree. If you change ten things and fix the issue, you will never know which on actually caused the issue, and may have created 9 additional problems later on.